Calories in Tuna: Nutrition Facts & Serving Sizes
Per 3 oz (85g)
Per 100g
Source: USDA FoodData Central, SR Legacy, March 2026.
A 3 oz (85g) serving of tuna contains about 122 calories with 19.8g of protein and 4.2g of fat. Per 100g, tuna provides 144 calories, 23.3g of protein, 4.9g of fat, and zero carbs. This data reflects light tuna (such as yellowfin). Tuna is one of the highest-protein, lowest-calorie foods available in any grocery store. The standout micronutrients are vitamin B12 at 9.4mcg per 100g (391% daily value), niacin at 8.7mg per 100g, and selenium at 36.5mcg per 100g (66% daily value). Vitamin A is notably high at 655mcg per 100g. Vitamin D at 5.7mcg per 100g makes tuna one of the best natural food sources of this vitamin. For anyone tracking macros, tuna is essentially a cheat code for hitting protein targets: a single 3 oz serving provides nearly 20g of protein at only 122 calories with virtually no prep work required. A can of tuna in water is the most convenient, affordable high-protein food on the market.
Nutrition Highlights
Calories by Serving Size
| Serving | Cal | Protein | Carbs | Fat | Fiber |
|---|---|---|---|---|---|
| 3 oz (85g) | 122.4 | 19.8g | 0g | 4.2g | 0g |
| 100g | 144 | 23.3g | 0g | 4.9g | 0g |
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Full Nutrition Facts (per 100g)
| Nutrient | Amount | % Daily Value |
|---|---|---|
| Calories | 144 | 7% |
| Protein | 23.3g | 47% |
| Total Fat | 4.9g | 6% |
| Saturated Fat | 1.3g | 7% |
| Total Carbohydrates | 0g | |
| Dietary Fiber | 0g | |
| Sugars | 0g | |
| Sodium | 39mg | 2% |
| Cholesterol | 38mg | 13% |
Vitamins & Minerals (per 100g)
| Nutrient | Amount | % Daily Value |
|---|---|---|
| Saturated Fat | 1.3g | 0% |
| Cholesterol | 38mg | 13% |
| Calcium | 8mg | 1% |
| Iron | 1mg | 6% |
| Potassium | 252mg | 5% |
| Vitamin A | 655mcg | 73% |
| Vitamin D | 5.7mcg | 29% |
| Vitamin B6 | 0.5mg | 29% |
| Vitamin B12 | 9.4mcg | 392% |
| Magnesium | 50mg | 12% |
| Phosphorus | 254mg | 20% |
| Zinc | 0.6mg | 5% |
| Selenium | 36.5mcg | 66% |
| Folate | 2mcg | 1% |
| Thiamin (B1) | 0.2mg | 17% |
| Riboflavin (B2) | 0.3mg | 23% |
| Niacin (B3) | 8.7mg | 54% |
% Daily Values based on a 2,000 calorie diet (FDA reference).
Health Benefits of Tuna
Tuna is one of the most protein-dense whole foods available. The 23.3g of protein per 100g is complete protein (all nine essential amino acids), making it as effective as chicken or beef for supporting muscle protein synthesis. At only 144 calories per 100g, the protein-to-calorie ratio is exceptional, better than chicken breast on an absolute basis.
The 9.4mcg of vitamin B12 per 100g covers nearly four times the daily recommended intake in a single 100g serving. Vitamin B12 is essential for red blood cell production, nerve function, and DNA synthesis. It is found only in animal foods, and deficiency causes fatigue and neurological issues. Regular tuna consumption makes B12 deficiency virtually impossible.
Selenium at 36.5mcg per 100g covers 66% of the daily value. Selenium is an antioxidant mineral that supports thyroid function and immune defense. Combined with the 5.7mcg of vitamin D per 100g, tuna gives you a micronutrient profile that most other protein foods do not come close to.
The 8.7mg of niacin (vitamin B3) per 100g supports energy metabolism and cellular repair. This is 54% of the daily value from a single 100g serving.
For practical use, canned tuna in water is one of the most cost-effective high-protein foods available. Mix it with mustard and eat it on rice cakes, add it to a salad, or make a quick tuna wrap. A can typically contains about 142g of tuna (two 3 oz servings), providing around 40g of protein for roughly a dollar or two.
Dietary Considerations
Tuna is naturally gluten-free and dairy-free, but not suitable for vegetarian or vegan diets. It is ideal for keto with zero carbs and high protein. Tuna is also paleo and Whole30 compliant. For weight loss, tuna is one of the best foods available due to its extreme protein-to-calorie efficiency. The low sodium content (39mg per 100g) makes it one of the lower-sodium seafood options. Note: tuna (particularly albacore/white tuna) contains mercury, so health guidelines generally recommend limiting consumption to two to three servings per week. Light tuna (skipjack) has lower mercury levels than albacore and can be eaten more frequently.
Daily Intake (100g)
100g of tuna provides 7% of a 2,000-calorie diet.
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Frequently Asked Questions
How many calories in tuna?
A 3 oz (85g) serving of tuna has about 122 calories. Per 100g, tuna contains 144 calories. A standard can of tuna in water (about 142g drained) contains approximately 204 calories and 33g of protein. Tuna is one of the highest-protein, lowest-calorie foods available.
Is tuna good for weight loss?
Tuna is one of the absolute best foods for weight loss. At 144 calories per 100g with 23.3g of protein and zero carbs, it maximizes protein intake while minimizing calories. High protein intake preserves muscle mass during a calorie deficit and increases satiety, making it easier to stick to your calorie targets.
How much protein in tuna?
Tuna contains 23.3g of protein per 100g, one of the highest protein densities of any whole food. A 3 oz serving (85g) provides 19.8g of protein. A full standard can (about 142g drained) provides around 33g of protein for approximately 204 calories.
How much tuna can I eat per week?
For light tuna (skipjack, lower mercury), most guidelines suggest up to three to four servings per week is safe for most adults. For albacore (white) tuna, which has higher mercury levels, limit to two servings per week. Pregnant women and young children should follow more conservative guidelines from their healthcare provider.
Is canned tuna as healthy as fresh?
Canned tuna retains most of the protein and micronutrients (B12, selenium, vitamin D) found in fresh tuna. The main trade-off is that omega-3 content varies. Tuna packed in water retains more omega-3s than tuna packed in oil, which leaches some omega-3s into the oil that gets drained off. For overall nutrition, canned tuna in water is an excellent and affordable option.
Is tuna good for building muscle?
Yes. Tuna provides 23.3g of complete protein per 100g with all essential amino acids needed for muscle protein synthesis. The combination of high protein, low calories, and rich B12 content (important for energy and nerve function) makes it a top choice for both bulking and cutting phases. It is one of the most cost-effective muscle-building foods available.
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